The first-ever bus route between London and Delhi is set to debut in 2021 - and will set the world-recorded for the longest operational bus journey.

But how long will it take - and which countries will it travel through? If you're up for the travel adventure, here's everything you need to know.

How long will the journey from London to Delhi take by bus?

It will head through 18 countries over 70 days.

Operators Adventures Overland have described the marathon tour as “the first ever hop-on/hop-off bus service” between the two cities, and the intervening itinerary spans the Great Wall of China and the Brandenburg Gate.

What will the route be?

After leaving Delhi, the bus will head east through Nepal and Bhutan, turning south to sample the pagodas of Myanmar and the bars of Bangkok.

The route then tracks a huge arc northwards through China and negotiates three of the seven ‘stans’, before arrowing into Eastern Europe via Moscow.

Latvia, Lithuania, Poland, the Czech Republic, Germany, Belgium, the Netherlands and France all feature on the European leg of the journey, before the bus finally crosses the channel and terminates in the UK.

Who founded the travel company that will operate the route?

Adventures Overland was founded by entrepreneurs and tireless globetrotters Tushar Agarwal and Sanjay Madan, who have form for eye-poppingly long journeys.

The pair previously held the record for longest journey by car in a single country (17,107 kilometres, in Australia), while Bus To London was part-inspired by a similar journey Agarwal made in 2010.

Is the route new?

Not really, the route is not entirely new, and in the Fifties and Sixties a host of banged up buses and campervans used to ferry backpackers between Europe and South Asia on the so-called ‘Hippie trail’.

The new service deliberately mimics a 1957 journey on a bus nicknamed ‘The Indiaman’, which traversed an even longer route between London and Kolkata.

What is the current world’s longest bus route?

The current world’s longest bus route bisects South America, running for 6,200 kilometres between Peruvian capital Lima on the shores of the Pacific, to Brazilian megacity Rio de Janeiro on the Atlantic coast. At 20,000km, London to Delhi is further than that, even in a straight line.